[SalesForce] How to get the base URL in the formula editor

Use a chrome browser right click and say inspect element.

Say for eg. you want to include the name of the field "website" for using in your URL param

Right click on the website input field and you should the screen split into half and show the raw code like

<div id="acc12_ileinner" style="display: none;">&nbsp;</div>

Use the Id in your URL acc12_ileinner= "yahoo.com"

As we can see on the other post, you need to query the account object to retrieve the entitlementId and then set it on the case. Please find below the updated code in which we have queried on the account object to get the entitlementId and set it on the case record. Also, you have hardcoded the recordType ID and the owner fields which is not a good practice and will definitely fail when you migrate to production. The code below shows how you should query the recordTyeId using the developer name and then set it on the record. Similary, query for the groupName and get the id to set it as the owner.

{!REQUIRESCRIPT("/soap/ajax/29.0/connection.js")} 
var myquery = "SELECT  Application_Entitlement_ID__c  FROM Account WHERE Id = '{!Opportunity.AccountId}' limit 1";

result = sforce.connection.query(myquery); 
records = result.getArray("records"); 

if(records[0]){ 
var relatedAccount = records[0]; 
try{ 
    var recToCreate = new sforce.SObject("Case");
    // TODO: update the filter with your record type name
    var recordTypeQuery = sforce.connection.query("SELECT name,Id from RecordType where developername = 'yourRecordTypeName'");
    var recordTypeQueryResult = recordTypeQuery.getArray("records");
    recToCreate.RecordTypeId = recordTypeQueryResult[0].Id;
    // select Queue as owner 
    var queueNameQuery = sforce.connection.query("SELECT Queue.Name, QueueId from QueueSobject where Queue.Name = 'WE Customer Services'");
    var queueNameQueryResult = queueNameQuery.getArray("records");
    recToCreate.OwnerId = queueNameQueryResult[0].QueueId;  
    recToCreate.AccountId = '{!Opportunity.AccountId}';  
    recToCreate.Subject = '{!Opportunity.Name}';  
    recToCreate.Origin = "Customer Application";
    recToCreate.Opportunity__c = '{!Opportunity.Id}';
    recToCreate.User__c = '{!Opportunity.OwnerId}';
    recToCreate.EntitlementId = relatedAccount.Application_Entitlement_ID__c;
    var result = sforce.connection.create([recToCreate]); 

    if(result[0].success == "true"){
        location.reload();
    }
    else{
        alert("An Error has Occurred. Error:" + result[0].errors.message);
    }
}
catch(e){
    alert("An Error has Occurred. Error:" + e);
}

}